<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .sjx {
            width: 0;
            height: 0;
            border: 10px solid transparent;
            border-top-color: black;
        }

        .sjx::before {
            content: attr(tooltip-data);
        }
    </style>
</head>

<body>
    <div class="sjx" tooltip-data="让我康康！"></div>
</body>

</html>